Langerhans cell histiocytosis of bone: MR imaging.

Magnetic resonance (MR) images of 12 pathologically proven lesions of Langerhans cell histiocytosis (LCH) of bone were reviewed retrospectively. MR identified all lesions, three of which were not identified on plain radiographs. In all cases, MR showed greater abnormality than did plain radiographs. With one exception, all lesions were hypointense on T1-weighted images and hyperintense on T2-weighted images. The lesions and associated soft tissue abnormalities were very conspicuous on short TI inversion sequences and T1-weighted post-contrast images. Follow-up MR studies in two patients after chemotherapy showed decreased size and enhancement of lesions compared with baseline studies.